1. Field
The present invention relates to a material for organic electroluminescence device (also referred to as “an organic EL device material”), an organic electroluminescence device (also referred to as “an organic EL device”), a manufacturing method of a compound used therein, and a light emitting apparatus and an illuminating apparatus using the same device.
2. Description of the Related Art
Since organic electroluminescence devices are capable of obtaining high luminance light emission by low voltage driving, they are actively researched and developed in recent years. An organic electroluminescence device generally has a pair of electrodes and at least one organic layer including a light emitting layer between the pair of electrodes, and electrons injected from the cathode and holes injected from the anode are recombined in the organic layer, and generated energy of exciton is used for emission of light.
Increment in efficiency of devices has been advanced by the use of phosphorescent materials. Iridium complexes and platinum complexes are known as the phosphorescent materials, and a platinum complex light emitting material capable of light emission of blue to green is reported. There is disclosed in US 2008-0297033 a complex of a ligand having a condensed ring structure and iridium or platinum. A platinum complex using a tetradentate ligand having a symmetrical structure of allylazole is disclosed in JP-A-2007-096255. The light emitting layer of an organic electroluminescence device using emission of phosphorescence is formed by the addition of a phosphorescent material to a material transporting charge (a host material).
A phosphorescent material theoretically necessitates wider energy gap than a fluorescent material. In particular, in a blue region going through a light emitting process from a high energy state, since great electric load is applied to the phosphorescent material, development of a blue phosphorescent material capable of achieving high efficiency and high durability in a pure blue region of short wavelength has been difficult. There has been reported recently in US 2008-0297033 that devices using an Ir metal complex having a condensed heterocyclic ring as a bidentate ligand as the phosphorescent material show high durability. However, it is known that the light emitting efficiency of such devices is as low as 4 to 6% to theoretically capable light emitting efficiency of 20% of phosphorescent materials. Although the light emitting efficiency of such devices can be improved by the introduction of a substituent into a specific position, but it is reported that the durability lowers in such devices, so that the compatibility of performances cannot be attained yet. Each of the ligands on Ir is independent from each other and the metal complex has a bulky structure having condensed four rings, so that it is presumed due to the fact that the route of thermal deactivation of energy by structural change is great. Further, the structure of the complex is liable to change by the introduction of a substituent, and the bond length between the ligand and Ir easily changes, which presumably lowers the durability.
In US 2008-0297033 and US 2007-0190359 are also reported the methods of synthesizing alkylphenanthridine which is a useful intermediate for the synthesis of a metal complex compound. However, it has been clearly shown by the examinations of the present inventors that the efficiency of reaction from compound 1 to compound 2 in the following reaction scheme is bad and the yield of compound 2 is low.
